GB2104308A - Electrical apparatus - Google Patents

Abstract

In order to facilitate the insertion of an electrical apparatus such as a dimmer switch or "torpedo" switch into an electric cable having at least two separate conductive cores, the apparatus comprises two separate terminal banks (9) each of which comprises at least three conductive terminals (10). Each of the three terminals (10) in one bank (9) is at substantially the same distance from a corresponding one of the three terminals (10) in the other bank (9) and this avoids the necessity for graduating the lengths of the core ends where the cable is cut and thus significantly simplifies installation in a cable, particularly for an amateur electrician. <IMAGE>

Description

SPECIFICATION Electrical apparatus This invention relates to electrical apparatus of the kind which is intended to be interposed in a two- or three-core cable between a source of electrical energy and a unit that is to be controlled, or at least affected in some way, by the apparatus. amples of such apparatus include "torpedo" switches and rheostatic dimmers.

Known apparatus of the kind set forth can be difficult to install correctly in a cable, particularly for an amateur electrician, because , except for a very few examples of "torpedo" switches and the like that can be connected into a cable having a maximum of only two cores, the core ends have to be cut so as to project from the cable sheath by different distances for correct co-operation with terminals of the known apparatus.In particular, in the case of known apparatus intended for use in a three-core ''mains" cable, the "live" and "neutral" core ends have to project from the cable sheath by shorter distances at the installation point than do the ends of the "earth" core, the latter sometimes being capable of unbroken "straight-through" installation whilst the former two cores have to be cut and have their ends appropriately shortened.

The present invention seeks to overcome, or at least very significantly to reduce, this difficulty and accordingly provides an electrical apparatus of the kind set forth, wherein the apparatus includes two terminal banks having three terminals per bank, which banks are so arranged that each of said three terminals in one of them is at the same or substantially the same distance from a corresponding one of said three terminals in the other bank.

For a better understanding of the invention, and to show how the same may be carried into effect, reference vill now be made by, way of example, to the accompanying drawings, in which: Figure 1 is an exploded perspective view of electrical apparatus in accordance with the invention in the form of a "mains" dimmer switch having a longitudinally movable sliding control, Figure 2 is a vertical longitudinal section of the dimmer switch of Fig. 1, in an assembled condition, taken on the line ll-ll in Fig. 3, Figure 3 is a horizontal section taken on the line Ill-Ill in Fig. 2, and Figure 4 is a section taken on the line IV-IV in Fig. 3.

Referring to the accompanying drawings, the dimmer switch which is illustrated therein is only an example of electrical apparatus in accordance with the invention and comprises a base plate 1, a co-operating cover 2 and a dimmer mechanism 3, said mechanism 3 having a mounting plate 4 which, when the dimmer is assembled, seats snugly in a matchingly shaped oblong recess 5 in the base plate 1. The dimmer switch is relesably held together, when assembled, by two machine screws 6 (not shown in Figs. 2 and 3) whose shanks are entered through corresponding holes 7 in the base plate 1 and into blind screwthreaded bores 8 formed in internal portions of the cover 2.The dimmer mechanism is not fixedly secured to either the base plate 1 or the cover 2 but, when those parts are clamped to one another by the screws 6, the mechanism 3 is trapped in a fixed position between internal portions of the cover 2 and the oblong recess 5 in the plate 1.

The upper surface of the oblong mounting plate 4 of the mechanism 3 carries, adjacent its parallel shorter edges and alongside one of the two parallel longer edges thereof, two identical or substantially identical banks 9 each comprising three terminals 10 of the well known circular socket and transverse clamping grub screw type. It will be seen from the drawings that, in accordance with the invention, each of said three terminals 10 in one of the banks 9 is at the same or substantially the same distance from a corresponding one of the three terminals 10 in the other bank 9.This has the important advantage, particularly for an amateur electrician, that, when the dimmer is to be interposed in a three-core cable between a source of electrical energy in the form of a 240 volt main and an electric lamp or other unit that is to be controlled by the dimmer, only a single cut has to be made in that three-core cable whereafter the three core ends in the two halves of the split cable are respectively stripped of insulation and are connected in a conventional manner to the three terminals 10 of the corresponding bank 9.No graduation in the length of the projecting ends of the three cores of the two cable halves is required nor is any folding of one of the cores into the casing of the dimmer required to achieve an effective shortening of the length of that particular core as in the case of already known apparatus of the kind set forth at the beginning of this description. Although not shown in the drawings, each bank 9 may be marked, to identify the individual terminals 10, with the letters "L", "N" and "E" to identify live, neutral and earth, respectively and/or with the new internationally agreed colours brown, blue and green/yellow.

Once the cores of the cut cable have been appropriately connected to the six terminals 10 of the loose dimmer mechanism 3, its mounting plate 4 is replaced in the recess 5 and portions of the cable that are close to its cut ends are placed in lower parts 11 of a cord grip which also comprises shaped recesses 1 2 at the opposite ends of the cover 2, said parts 11 and recesses 1 2 co-operating to grip the two halves of the cable firmly when the cover 2 is replaced and the screws 6 are reinserted and tightened.

The dimmer mechanism 3 will not be described in detail since its construction and function are not primary features of the present invention. It suffices to say that the lower surface of the insulating mounting plate 4 carries a number of copper or other metallic conductors to which various electrical items mounted on the upper surface of the same plate 4 are appropriately connected, these items including the terminals 10 of the two banks 9. One of the items on the upper surface of the mounting plate 4 is a longitudinal slideway 1 3 along which a slider 14 is movable, said slider 14 r6 projecting upwardly through a slot 1 5 in the top of the cover 2 when the dimmer is completely assembled.

An operating knob (not shown) firmly but releasably engages the slider 14 LB in a frictional manner immediately above the slot 1 5 and can be used by an operator of the dimmer to switch off a table lamp or the like completely (slider 14 at one end of the slot 1 5) or to operate that table lamp or the like at full power (slider 1 4 at the opposite end of the slot 15). The slider 14 can, of course, be arranged at any chosen intermediate position along the slot 15, as may be required, and will give a degree of brightness of the table lamp or the like that is intermediate between "off" and "full power" dependent upon the particular position which is actually chosen.

The dimmer that has been described may merely rest freely on the surface of a table or other support but could, as an alternative for some installations, be fixedly secured to an appropriate support.

It is again emphasised that the dimmer which has been described is merely an exam ple of an electrical apparatus which may be constructed in accordance with the present invention. The described and illustrated dimmer mechanism 3, which exhibits a longitudinally movable sliding control in the form of the part of the slider 14 which projects upwardly through the slot 1 5 to receive an insulating knob, could be replaced by a rotary dimmer mechanism having a manually turnable knob adjustable between a "fully off" setting and a "full power" setting. A "torpedo" switch could advantageously be constructed in accordance with the invention.

Conventionally, "torpedo" switches that are to control low power consumption lamps and the like in a simple on/off manner do not include an "earth" conductor but a "torpedo" switch constructed in accordance with the invention can be used both for applications of that kind and for heavier power consumption applications such as the on/off control of, for example, the element of an electric kettle or an electric iron.Under these latter circumstances, particularly where the frame of the kettle, iron or the like is metallic, it is necessary that an "earth" connection should be employed and a "torpedo" switch having two banks 9 of terminals 10 which are arranged in a similar manner to those described above will merely need to be installed in the three-core cable supplying power to such a unit substantially exactly as set forth for the previously described dimmer, the same simplicity of installation being available. If a "torpedo" switch or other electrical apparatus constructed in accordance with the invention is to be used in a two-core cable, then only the two terminals 10 in each bank 9 that are respectively marked "L" (live) and/or brown and "N" (neutral) and/or blue are used leaving the two terminals 10 marked "E" (earth) and/or green/yellow entirely free of any external connection.It will be appreciated that, in any "torpedo" switch or the like constructed in accordance with the invention, there will merely be three rigid or semi-rigid conductors interconnecting the three pairs of substantially equally spaced apart terminals 10, such conductors being split internally of the switch or the like in such positions that a transversely movable dolly carrying spaced conductive rings or the like can occupy a setting in which those rings close the openings in the three conductors or a setting in which the openings in the three conductors remain unbridged. Usually, a spring-loaded detent or the like will be incorporated to ensure that a positive application of force to the dolly is necessary to move it from the "on" position to the "off" position or vice versa.

Each of the two banks 9 of three terminals 1 0 that is provided in the relationship that is required in accordance with the present invention is advantageously in the form of a unitary block having the three terminals 10 built into it but this is not, of course, essential and each bank 9 may comprise three separate insulators having respective terminals 10 built into them or even three metallic terminals separately secured to an insulating base or support to form a bank that is not actually physically embodied in at least one insulator. Although each bank of terminals should comprise three of those terminals, it could, if required, comprise a plurality of terminals in excess of three where an electrical apparatus constructed in accordance with the invention is to be interposed into a cable having four or more cores.

Although the primary intention of electrical apparatus in accordance with the invention is for interposition in a cable between a 240 volt, 50 Hz or other source of "mains" energy and some electrical unit that is to be controlled, or at least affected in some way, by that apparatus, this is not essential and an apparatus constructed in accordance with the invention may be used with sources of alter nating current or of direct current at both higher and lower voltages than those supplied by domestic single-phase alternating current "mains". It will, of course, also be understood that terminals, such, purely for example, as solder tags, other than the well known terminals 10 which have been described above can equally well be employed in an electrical apparatus constructed in accordance with the invention.

Claims (11)

1. An electrical apparatus of the kind set forth, wherein the apparatus includes two terminal banks having three terminals per bank, which banks are so arranged that each of said three terminals in one of them is at the same or substantially the same distance from a corresponding one of said three terminals in the other bank.

2. An apparatus as claimed in claim 1, wherein the apparatus is in the form of a dimmer switch.

3. An apparatus as claimed in claim 2, wherein the dimmer switch comprises a longitudinally movable sliding control.

4. An apparatus as claimed in claim 2, wherein the dimmer switch comprises a rotary control.

5. An apparatus as claimed in any one of claims 2 to 4, wherein the dimmer switch is constructed in such a way that it can rest freely upon a table top or like support.

6. An apparatus as claimed in any preceding claim, wherein at least one of the two terminal banks is physically embodied in an insulating block having the corresponding conductive terminals built into that block.

7. An apparatus as claimed in any preceding claim, wherein at least one of the terminal banks takes the form of at least three separate insulators having the corresponding conductive terminals built into those respective insulators.

8. An apparatus . ) claimed in any preceding claim, wherein at least one of the terminal banks takes the form of at least three conductive terminals separately secured to at least one insulating base plate or other support.

9. An apparatus as claimed in any preceding claim, wherein at least one of the terminals is in the form of a conductive socket provided with a transversely extending clamping grub screw.

10. An apparatus as claimed in claim 1 or in any one of claims 6 to 9 when read as appendant to claim 1, wherein the apparatus is constructed in the form of a "torpedo" switch.

11. An electric kettle or electric iron whose power supply cable has interposed therein a "torpedo" switch as claimed in claim 1 or in any one of claims 5 to 9 when read as appendant to claim 1.

1 2. A dimmer switch or ''torpedo'' switch of the kind set forth comprising two terminal banks constructed and arranged substantially as hereinbefore described with or without reference to the accompanying drawings.

1 3. A dimmer switch of the kind set forth substantially as hereinbefore described with reference to the accompanying drawings.

11. An apparatus as claimed in any preceding claim, wherein the apparatus is ofo elongate formation and is provided with cable clamps at, or adjacent to, its opposite ends.

1 2. An electric table lamp whose power supply cable has interposed therein an electrical apparatus as claimed in any preceding claim.

1 3. An electric kettle or electric iron whose power supply cable has interposed therein an electrical apparatus as claimed in claim 1 or in any one of claims 6 to 11 when read as appendant to claim 1.

14. An electrical apparatus of the kind set forth comprising two terminal banks constructed and arranged substantially as hereinbefore described with or without reference to the accompanying drawings.

1 5. An electrical apparatus of the kind set forth and taking the form of a dimmer switch substantially as hereinbefore described with reference to the accompanying drawings.

CLAIMS (12 Nov 1981)

1. An electrical dimmer switch or "torpedo" switch of the kind set forth, wherein the switch includes two terminal banks having three terminals per bank, which banks are so arranged that each of said three terminals in one of them is at the same or substantially the same distance from a corresponding one of said three terminals in the other bank.

2. A dimmer switch as claimed in claim 1, wherein the switch comprises a longitudinally movable sliding control.

3. A dimmer switch as claimed in claim 1, wherein the switch comprises a rotary control.

4. A dimmer switch as claimed in claim 2 or claim 3, wherein the switch is constructed in such a way that it can rest freely upon a table top or like support.

5. A dimmer switch or "torpedo" switch as claimed in any preceding claim, wherein at least one of the two terminal banks is physically embodied in an insulating block having the corresponding conductive terminals built into that block.

6. A dimmer switch or "torpedo" switch as claimed in any preceding claim, wherein at least one of the terminal banks takes the form of at least three separate insulators having the corresponding conductive terminals built into those respective insulators.

7. A dimmer switch or "torpedo" switch as claimed in any preceding claim, wherein at least one of the terminal banks takes the form of at least three conductive terminals separately secured to at least one insulating base plate or other support.

8. A dimmer switch or "torpedo" switch as claimed in any preceding claim, wherein at least one of the terminals is in the form of a conductive socket provided with a transversely extending clamping grub screw.

9. A dimmer switch or "torpedo" switch as claimed in any preceding claim, wherein the switch is of elongate formation and is provided with cable clamps at, or adjacent to, its opposite ends.

1 0. An electric table lamp whose power supply cable has interposed therein a dimmer switch or "torpedo"' switch as claimed in any preceding claim.